Omaha's nurses can override my doctor and state disability office

I filed for my short term disability claim on May 14th. I am having awful back and leg pain and can not sit or stand for any time period. Since then I have had to make repeated phone calls to Mutual of Omaha and had my doctors send medical records and MRI results to them. I was denied. I was told their nurse didn’t feel enough was being done by my doctors (who has me out on state disability at least until January 1, 2013). Since went does a nurse override a doctor and my state disability office. I have appealed and was again denied and told in so many word that I could go to work. I will be call the state Insurance Commission on Monday and a lawyer after that to see what can be done. I also have had to continue paying for the insurance all this time.